The present invention relates generally to communication systems and, in particular, to arbitrating service requests within communication systems.
Dispatch communication systems, such as the xe2x80x9ciDENxe2x80x9d communication system sold by xe2x80x9cMOTOROLAxe2x80x9d, enable a group of users to converse simultaneously. That is, one member of a group may talk to all the other members of the group in a broadcast fashion. Typically, each user of the group has a communication unit with a push-to-talk (PTT) button. To talk to the rest of the group, a user depresses the PTT button on his or her communication unit and continues depressing the PTT button while speaking. When finished or to allow another user of the group to speak, the user releases the PTT button. Another user may then speak by depressing his or her PTT button.
Only one group member may speak to the group at a time, but multiple group members may depress their PTT buttons to speak next. When a PTT button is depressed, the communication unit sends a PTT request to the infrastructure. The infrastructure must then arbitrate among all the PTT requests received, granting one request and denying the rest.
Today, there are two general approaches to performing this arbitration, centralized and decentralized arbitration. With centralized arbitration, all arbitration decisions for the system are made by a single arbitrator. With decentralized arbitration, all arbitration decisions for a given group""s dispatch session are performed by a single arbitrator; however, the system may contain multiple arbitrators which share the burden of arbitrating all the system""s requests.
As such dispatch systems expand and provide dispatch service to more and more subscribers (communication units), the number of PTT requests that must be arbitrated also expands. In a system that employs centralized arbitration, the single arbitrator may not have the processing power to keep up with the requests from the expanding subscriber base. In contrast, decentralized arbitration allows more arbitrators to be added to address the scalability issue. However, in both approaches, all request messaging must be conveyed by the infrastructure equipment to the particular arbitrator that will make the grant or deny decisions. Infrastructure bandwidth and processing power are utilized for the purpose of passing the request messaging to the appropriate arbitrator. In the end, such design requirements contribute to the equipment cost of systems. Conversely, limiting such design requirements, and thereby increasing the efficiency of the arbitration process, would likely contribute to equipment cost reductions.
Therefore, a need exists for an apparatus and method for arbitrating service requests in a more efficient and scalable manner.